1. Field of the Invention
The present invention relates to a substrate processing method and substrate processing system for performing a gas process on a target substrate, such as a semiconductor wafer, while supplying a process gas onto the target substrate, and also to a computer readable storage medium that stores a program for controlling the substrate processing system.
2. Description of the Related Art
In recent years, in the process of manufacturing semiconductor devices, a method called “chemical oxide removal (COR) process” has attracted attention as a method alternative to dry etching or wet etching for realizing a fine etching process.
As a method of this kind for etching a silicon dioxide (SiO2) film formed on the surface of a target object, such as a semiconductor wafer, the following process is known (for example, see US 2004/0182417 A1, US 2004/0184792 A1, and Jpn. Pat. Appln. KOKAI Publication No. 2005-39185). Specifically, while the temperature of the target object is adjusted under a vacuum state, a mixture gas of hydrogen fluoride (HF) gas and ammonia (NH3) gas is supplied into a chamber. The mixture gas reacts with the silicon dioxide and generates ammonium fluorosilicate ((NH4)2SiF6). The ammonium fluorosilicate is heated and thereby sublimed in the subsequent step, so that the silicon dioxide film is consumed and etched from the surface.
In recent years, since semiconductor devices are being miniaturized, the integration level of semiconductor integrated circuit devices is being increased. With an increase in the level of miniaturization and integration, the size of contact holes formed in semiconductor integrated circuit device chips becomes smaller and the number of contact holes formed in each chip becomes larger.
The COR described above is effective for removing a silicon dioxide film formed at the bottom of contact holes, i.e., a so-called natural oxide film, which has been generated in forming the holes.
However, as the size of contact holes is smaller and the number of contact holes is larger, fluorine and/or fluorine compound are more likely to be left as residues in the contact holes. If a reactive halogen and/or halogen compound, particularly fluorine and/or fluorine compound, are left in the contact holes, they may cause abnormal reactions with components of integrated circuits, such as a silicon substrate, gate electrodes, gate electrode sidewall insulating films, inter-level insulating films, and interconnection layers. Such abnormal reactions deteriorate the yield of semiconductor integrated circuit devices.